WO2007090192A2

WO2007090192A2 - Stable one-part aqueous tooth whitening composition

Info

Publication number: WO2007090192A2
Application number: PCT/US2007/061477
Authority: WO
Inventors: Jr. James J. Longo; William A. Mchale
Original assignee: Premier Dental Products Company
Priority date: 2006-02-01
Filing date: 2007-02-01
Publication date: 2007-08-09
Also published as: JP2009525352A; EP1986953A2; JP5654201B2; EP1986953A4; AU2007211012A1; US20070202059A1; US8574555B2; WO2007090192A3; CA2637266A1

Abstract

The invention relates to a high-temperature stable, one-part, aqueous tooth bleaching composition for contacting a tooth surface. The composition comprises a bleaching agent comprising a high level of a aqueous hydrogen peroxide. The bleaching agent is derived from multiple components within the composition and comprises at least about 15% by weight of the total composition weight. The Composition also comprises a bleaching agent stabilizer comprising from about 0.01% to about 1.00% by weight of the total composition weight.

Description

STABLE ONE-PART AQUEOUS TOOTH WHITENING COMPOSITION

CROSS-REFERENCE TO RELATED APPLICATIONS [0001 ] The present application, claims the benefit of U.S. Provisional Application No.

60/764,072 filed on February 1 , 2006, which is .incorporated .herein by reference

STATEMENT REGARDING FEDERALLY

SPONSOREDRESEARCHOR DEVELOPMENT [^'0002] The present invention was not developed with the use of any Federal Funds, but was developed independently by the inventor.

BACKGROUND OFTHE INVENTION [0003] Tooth bleaching typically tnvoi ves the application of a peroxide containing composition to the surface of the tooth enamel to achieve & desired whitening effect The most com mon peroxide donor ingredients are, but are not limited to_t carbarøide (urea) peroxide and hydrogen peroxide. The latter has become the tooth bleaching materia! of choice due to its ability to whiten teeth faster than higher concentrations of carbamide peroxide. Additionally, aqueous tooth wh itening gels have proven desirable due to the hydrating effects on the structure of the tooth, reducing the likelihood of tooth sensitivity. As such, it is desirable to achieve stable aqueous hydrogen peroxide tooth whitening gels for commercial preparation,

10004 j Aqueous hydrogen peroxide tooth bleaching formulations have their limitations however. Until recent years, stable aqueous hydrogen peroxide tooth bleaching gels have been virtually non-existent. Hydrogen peroxide is a powerful oxidizing agent and an. unstable compound that decomposes readily over time into water and oxygen. Certain chemical and physical influences can accelerate the rate of decomposition and need to be controlled for a $table tooth whitening gel. to exist. Temperature, pH and errant metal ions all have a profound effect, on the decomposition of hydrogen peroxide, particularly in an aqueous formula. Aqueous tooth whitening gels comprising high levels of hydrogen peroxide are defined as comprising an available hydrogen peroxide concentration, equal to or greater than, about 15% of the total composition weight up to and including about 40% of the total composition weight. Generally, th ese high level hydrogen peroxide compositions require the gel. to be refrigerated to reduce the rate of decomposition., thus enabling ant increased shelf life. This process is difficult as well as expensive for commercial distributors to maintain adequate shelf life for salable product

{0005} To combat these limitations, high level hydrogen peroxide bleaching compositions are generally delivered to the end user in a two-part system packaged form mat maximizes peroxide stability. Packaging stabilized hydrogen peroxide solutions separately from other formulation ingredients is one method that enables manufacturers to meet required sheif life parameters. Two types of separation methods are dual barrel syringes and liquid hydrogen peroxide/powder systems. The disadvantages to these types of packaging are that the hydrogen peroxide must be mixed at the time of placement in the dental operatory, thus resulting in a loss of valuable chair time and the unwillingness for patients to prolong the tooth whitening experience. Additionally_, due to hydrogen peroxide's highly corrosive properties, peroxide burns from the splatter resulting from the spatulation of th e mix process are always a concern. There also exists the potential fora non-homogerseous mix

[ 0006] In office bleaching by dentists is the primary end xsse for high level hydrogen peroxide tooth whitening compositions. Therefore, it is imperative that the whitening compositions be formulated as one-part (no-mix) systems and maintain adequate shelf stability in order to guarantee efficacy at the time of placement by the dentist within the patient.

[0007] Most distributors of iti~office dental products require that a suitable shelf life be maintained for any given product Further, most distributors rely on a product to maintain a two year shelf stability. Shelf stability is generally determined by placing the product under abnormal or exaggerated storage conditions for a predetermined amount of time to ensure a. product's stability under normal storage conditions. Room temperature storage conditions, for a single component tooth bleaching composition, are desirable in order to eliminate costly and inconvenient storage problems. To a greater degree, & two year room temperature storage guarantee is what is required for distribution of a single component aqueous tooth bleaching composition.

[0008] The pH of an aqueous hydrogen peroxide tooth whitening composition also lias great bearing oti the stability of the gel. Hydrogen peroxide solutions are strongly acidic and maintain their stability in acidic pB formulas. Stable aqueous hydrogen peroxide tooth whitening gels caw be formulated in the acid pH range. However, bleaching compositions k\ the acidic pH range (pR 2.0-5.5) are prone to the demineralization of dental enamel by the solublizi ng calcium ions from the tooth surface. This reduction in surface enamel leads to tooth sensitivity and discomfort for the patient

{0009} Additionally, it. has been shown that peroxide containing tooth bleaching compositions are more effective at whitening teeth at higher pH levels than at lower pH level. Therefore it is desirous to obtain a single component, aqueous tooth bleaching composition with high levels of hydrogen peroxide that can maintain a non-refrigerated, two year shelf stability while exhibiting a neutral or basic pH or a pH of greater than about 5.5. Unfortunately, to date, no such commercial formula exists.

[0010] Recent, technology has shown single component, high-level aqueous hydrogen peroxide gels to be stable for short periods of time at. room temperature, ϊt is known that the presence of stabilizing agent s within the aqueous hydrogen peroxide tooth whitening formula can extend the life of the formula by slowing or eliminating the rate of peroxide decomposition.

Decomposition of tire peroxide within the formula can result in viscosity loss of the composition, expansion of the composition due to the evolution of oxygen gas and/or the loss of available hydrogen peroxide content

[0011] U.S. Patent No. 6,555.020 to Chadwick et άt disclose stable aqueous tooth whitening compositions containing high levels of hydrogen peroxide, €hadwϊek teaches the utilization of aminocarboxyiic acid/salt stabilizing agent s to prolong room temperature shelf stability and to maintain the gel characteristics of the composition. The stabilizing agents are selected from a group consisting of CaNa2EDTA, Na4EDTA_; and CDTA. However, Chadwick discloses that the greatest shelf stability is for a term of 84 days under room temperature storage conditions. While 84 days (12 weeks) is a sigαificaπt stability period for art elevated hydrogen peroxide level tooth whitening formula,, it fails to show long-term stability under exaggerated conditions and cart only be translated into a 12 week stability period for the composition. Thus₅ it fells considerably short of a desired two year shelf life required to becom e a salable product through commercial distribution.

[0012] U.S Patent No. 5.858,332 to Jensen ei at teach of a stable, one-part, premixed hydrogen peroxide tooth whitening composition that utilizes a bleaching agent stabilizer that ties up errant, metal ions that can result in decomposition of the bleaching agent within the tooth whitening composition. Jensen et aϊ describes a bleaching agent selected frorrs a group consisting of aqueous hydrogen peroxide, carbamide peroxide, sodium perborate a.ud mixtures th ereof. Additionally_., the whitening composition comprises a single thickenening agent, a carrier, and a bleaching agent, stabilizer selected from a group of edetate disodium, EDTA, oxine EDTA, calcium disodktm EDTA₅ adipic acid, succinic acid_., citric acid, tin .nitrates, tin phosphates and mixtures of the foregoing.

[0013] Jensen et aL claim a stable one-part dental, bleaching agent that maintains at least 95% of its original strength 1 month after its manufacture and at least 60% approximately 3 months after tbe compositions manufacture. However, Jensen et at. makes no mention of the stability under exaggerated aod/or accelerated storage conditions and it is understood that the stability occurs under room temperature conditions and for a maximum of 60 - 95% available hydrogen peroxide content after 3 months storage time. J0014J U.S. Patent Nos, 6,488,914; 6,331,292 and 6,221,341 to Montgomery detail aqueous tooth whitening compositions with neutral or alkaline pH levels. Montgomery teaches one-part, aqueous tooth whitening compositions that are formulated to be stable st high pH levels (6-10). The significance of this teaching is the ability to detail an aqueous hydrogen peroxide tooth whitening composition that is stable under neutral or alkaline conditions with a high water content with in th e composition. (>70%). However, Montgomery claims an available hydrogen peroxide content of less than 15% of the total weight of the composition, which fails far short of an elevated or high hydrogen peroxide concentration within the composition. Additionally, Montgomery makes no mention of extended storage stability as well as the stability of the compositions under exaggerated or accelerated temperature conditions.

JOO.1.5) U.S. Patent No. 6,500,408 to Chen details a tooth bleach that utilizes Polyvinylpyrrolidone as a thickening agent in combination with hydrogen peroxide. However, Chen stipulates that the PVP must be present in th e formula at a concentration of 25% or greater. Be makes no mention of multiple thickening agent s within the composition, nor is the PVP thickening agent a cross linked, poly pϊasdone polymer/hydrogen peroxide complex, contributing synergisticaily to the available hydrogen peroxide within the tote! bleach composition. Additionally, Chen makes no mention, of long term elevated temperature stability of the tooth bleaching composition.

{0916| In contrast, the present invention relates to a stable one-part, aqueous tooth whitening composition that utilizes high levels of hydrogen peroxide bleaching agent m a neutral gel formula (pH 6-7), The stability of th e composition is proven under accelerated and/or exaggerated storage conditions which translate into at least a two year shelf life for the composition under normal room temperature storage conditions. The stability of the composition is a critical function of known tooth whitening ingredients combined under unique parameters including weight percentages and ratios, for the elevated temperature stability to occur. Deviation outside the controlled composition window, results in predictable failure of the composition,

BRIEF SUMMARY OF THE INVENTION [0017} The invention relates to a high- temperature stable, one-part, aqueous tooth bleaching composition for contacting a. tooth surface. The composition comprises a. bleashing agent comprising a high level of a aqueous hydrogen peroxide. The bleaching agent is derived from multiple components within the composition and comprises at least about 15% by weight of the total composition weight. The Composition aJso comprises a bleaching agent stabilizer comprising from about.0.01 % to about 1.00% by weight of the total composition weight

[0018] In one preferred embodiment, th e bleaching agent is derived from, multiple components within the composition including an aqueous hydrogen peroxide, a polyplasdone hydrogen peroxide complex; a pol.yacrylic acid polymer; water; glycerin; ethyienediamiiietetraacetic acid, disodium salt; etidronic acid and ammonium hydroxide.

[0019] In one preferred form of the invention, the bleaching agent stabilizer comprises a 1 : 1. ratio of ethyienediamineietiaaceuc acid, disødium salt and etidronic acid. The ratio of hydrogen peroxide to bleaching agent stabilizer is about 25: .1 to about 60: 1. And, the ratio of hydrogen peroxide to bleaching agent stabilizer is about 25: .1 to about 60: I . The bleaching agent stabilizer may be selected from a group consisting of ethylenediamineteraacetic acid, disodiuπi salt; ethyl enediantiiieteraacetic acid, tetrasodtum salt; ethylenediamiaetetraacetic acid, calcium disodium salt; etidronic acid; citric acid; gluconic acid; sodium citrate; sodium gluconate: sodium phosphate; dbodruro. phosphate: trisodsυra phosphate; tetrapotassium pyrophosphate; sodium tripolyphosphate and potassium stannate. [_.0020] The toofh bleaching composition may also include a plurality of thickening agent s, the thickening age»ts comprising at least a crossUnked polyacryiic acid polymer and a polyptasdone hydrogen peroxide complex. In one form of the invention. The crossϊinked polyacryiic acid thickening agent comprises less than about 1.50% by weight of the total composition weight. The thickening agent s may comprise from. abotrt 5,0% to about 50.0% by weight of the total composition weight And, the poryplastkme hydrogen peroxide complex may comprise at. least about 10.0% by weight of the total composition weight.

[^'0021] The tooth bleaching composition may also include at least one chelating agent selected from the group consisting of ethylenediarnineteraacetic acid, disodium salt; ethylenediammeteraaeelie acid, tetxasodmm salt; ethylenediammeietsaacetic acid, calcium disodium salt; citric acid; gluconic acid; sodium citrate; sodium gluconate; sodium phosphate; disodiura phosphate; trisodium phosphate; tetrapotassium pyrophosphate; and sodium, tripolyphosphaie. The at least one chelating agent may comprise from about 0.01% to about 0.50% by weight of t he total composition weight. In one preferred embodim ent, the chelating agent, the chelating agent(s) may be disodium EDTA and/or etidronic acid.

}0022| The tooth bleaching composition may also include at least ones hygroscopic agent selected from the polyol group consisting of glycerin, polyethylene glycol, propylene glycol and sorbitol. The at least one hydroscopic agent may comprise from abou t.0% to about 10.0% by weight of the total composition weight. In one preferred embodiment, the hygroscopic agent is glycerin,

{ 0023J The tooth bleaching composition may also include at least one -neutralizing agent selected from a group consisting of triethanolam ine, troroethamine, sodium hydroxide, potassium hydroxide, and ammonium hydroxide. Th e at least one neutralizing agent , may adjust the pH of th e final tooth whitening composition between about 6.0 to about 7.0. Tlie at least one neutralizing agent may comprise from about 0.50% to about 5.00% by weight of the total composition weight. In one preferred embodiment, the at least one neutralizing agent is ammonium hydroxide.

DETAILED DESCRIPTION OF THE INVENTION [0024| The present invention is direct to a stable, one-part aqueous tooth whitening compositions containing high percentages of bleaching agent stable at elevated storage temperatures for extended periods of time. In particular, the invention relates to compositions that comprise a hydrogen peroxide bleaching agent derived from multiple sources present with in the aqueous tooth bleaching formula acting syπergisticaily to release elevated levels of peroxide to the tooth surface for a desired whitening effect while remaining stable -with, no appreciable decomposition of the bleach composition when subjected to accelerated stability testing involvirig storage temperatures from 40 degrees C to 47 degrees C for a predetermined amount of time.

} 0025| The tooth whitening compositions exhibit high temperature stability, based on retention of available hydrogen peroxide and net viscosity loss. Stability is defined as the ability of the composition not to lose more than about 10% of the gels initial available hydrogen peroxide content through about a 2 year time frame and remamtag viscous and substantially free of entrained oxygen bubbles resulting from decomposition of the peradde. The bleach compositions representative of th e present invention were tested through two elevated temperature storage conditions: about 40 degress C and about 47 degrees C depending upon available hydrogen peroxide content within the composition, The compositions maintain greater than 95% available hydrogen peroxide content after 12 weeks storage at 40 degrees C (104 degrees F) with no loss of gel viscosity. After 15 weeks at 40 degrees C, the compositions exhibit retention of greater than 94% available hydrogen, peroxide with little to no viscosity loss and greater than 90% available peroxide retention after 20 weeks with a slight loss in viscosity and pH. It should be understood that under accelerated stability testing protocol, a product formulation must survive for a minimum of .12 weeks at 40 degrees C in order to be assumed that it will survive on the open market, for a m inimum of two years under room temperature storage conditions (i.e. non-refrigerated storage). Likewise, a product formulation must survive for a minimum of 9 weeks at 4? degrees C to assume the same two year room temperature stability.

{0026} In one preferred compositions a hydrogen peroxide content of about .15 to 32% survived for an excess of 12 weeks at 40 degrees C with little to no loss of available hydrogen peroxide content. In a further preferred composition, a gel with a hydrogen peroxide content of about 15 to 32% survived i« excess of 4 weeks and 6 days at 47 degrees C with less than a 10% available hydrogen peroxide loss within the composition, In the most preferred composition, a hydrogen peroxide content of 15 to 20% survived in excess of 9 weeks at 47 degrees C with little to no loss of available hydrogen peroxide content. [ 0027] Critical to the stabii ity of the compositions are the presence of one or more chelating or stabilizing agent s incorporated in a precise ratio to the level of pe? oxide content within the formula creating a narrow window for elevated temperature stability to occur. Deviation outside the accepted window results in predictable failure for the whitening composition under the elevated temperature storage conditions, hi addition, the pB of the final composition has a narrow band in which stability of the gel will occur as well Λ pH that is greater than the upper limit threshold of the composition will result in predictable failure for the whitening composition. Stabilized aqueous hydrogen peroxide is the preferred bleaching agent with a minimum peroxide starting content of 35 to 50%.

|0028) It is the purpose of this application to describe the preferred embodiments of a tooth bleaching composition .made in accordance with the present invention. The preferred tooth bleaching composition contains high levels of hydrogen peroxide and exhibits stability at elevated storage temperatures. The present invention relies on a specific m ixture of ingredients combined under tight tolerances and specific mix procedures to attain a stable, one-part bleaching gel that can survive a two year, non-refrigerated sh elf life as required tor commercial distribution.

{0029} Hydrogen peroxide in its aqueous form is the preferred primary peroxide source. Stabilized hydrogen peroxide solutions are available commercially from a number of chemical manufacturers. The stabilized solutions are available m concentrations from approximately 3.0% to 90.0% based on a weight/weight analysis- Concentrated hydrogen peroxide solutions ranging from about 30 to 50% by weight or greater are preferred for providing the bulk of the hydrogen peroxide source within the bleaching composition of the present invention. The higher the

I l concentration of the initial hydrogen peroxide solution, the higher the final hydrogen peroxide concentration becomes within the final tooth whitening composition. Hydrogen peroxide solutions obtained from Solvay are the most preferred.

[0030] Due to the recent availability of linear and crossiinked Flasdone and Polyplasdone polymers eomplexecl with hydrogen peroxide, also known as Polyvinylpyrrolidone OPV.P)/hydroge« peroxide complexes or PEROXYDONE™ polymers manufact ured by International Specialty Products, foe, (ISP), aqueous peroxide solutions can be thickened while simultaneously increasing the available hydrogen peroxide concentration within the final composition. Higher levels of hydrogen peroxide translate into quicker bleaching times of vital teeth to obtain a desired tooth shade.

[0031 ] The stable, one-part, aqueous tooth whitening compositions of the present invention comprise hydrogen peroxide derived from multiple components within the composition. The compositions preferably comprise approximately 10% to 50% available hydrogen peroxide by weight of the total composition weight In one form of the invention_* an aqueous solution of 50% hydrogen peroxide is combined with & PVF/hydrogen peroxide complex to form an aqueous hydrogen peroxide gel or slurry. The 50% aqueous solution of hydrogen peroxide serves as the primary peroxide source for bleaching in the final composition, comprising about 75 % Lo about 99% of the available hydrogen peroxide. A PVP/hydrogen peroxide complex preferably comprising from about 17% to 22% available hydrogen peroxide by weight of the complex serves- as a secondary hydrogen peroxide source comprising about 1% to about 25% by weight of the available hydrogen peroxide in the final tooth whitening composition weight This unique combination of hydrogen peroxide donor sources within the composition serves to contribute to the stability of the final tooth bleach composition. Omission of either hydrogen peroxide donor source from the bleach composition results in decomposition and ultimately failure of the composition at elevated temperature storage conditions. In addition, compositions that are generated omittmg the poiyplasdone /hydrogen peroxide complex result m failure of the bleach composition under room temperature storage conditions as well.

[0032] IIn the present invention., at least one thickening agent present may be provided to facilitate viscosity modification of the tooth bleaching compositions, In one preferred form of the invention, at least two thickening agents are present The forming of a hydrogen peroxide gel serves as a two part function. First a thickened composition prevents the peroxide from migrating from the surface of the tooth to the surrounding soft tissue which can lead to gingival sensitivity and burns. Second, ϊi imparts an increase in retention time that the peroxide solution maintains its strength for release to the surface of the tooth.

[0033] In addition to a hydrogen peroxide source, the PVP,- hydrogen peroxide complex also serves as a thickening agent for the composition, tt ts preferably present witlun the composition at about 1% to 25% by weight of the total composition weight. More preferably ihe thickening agent is present in the composition at about 5,0% to 20.0% by weight of the total composition. At this level, the PVP complex thickens titc aqueous hydrogen peroxide to form a creamy paste or sticky gel of appropriate viscosity. The addition of a polyacrylic acid polymer as a secondary thickening agent allows the gel to be tailored to one of short rheoiogical flow and increased bioadhesion to ensure that the final composition clings to the surface of the teeth. The addition of the polyacrylie acid polymer utilizes a crosslinked structure to prevent syneresis ihat may occur within the composition over an extended period of tim e, thus increasing overall get stability.

[0034 ] In the present invention, the more preferred PVP/hydrogea peroxide complex is the crossiinked polypiasdone polymer. The crossiinked polypiasdone polymers exhibit insolubility in water, however, they swell rapidly in the presence of water to form a thickened matrix. Ae sucfe. the hydrogen peroxide is easily dissociated, from the poJypϊasdone polymer, thus releasing it to the surrounding aqueous media for bleaching availability. The preferred, polyptasdone'liydrogen peroxide complex is marketed by International Specialty Products Corporation under the trade name P.EROXYDQNE XL-10 and maintains a particle size limit of approximately 60-100 microns.

[0035} It is known that polyacrylic acid polym ers exhibit, a high degree of incompatibility with certain ingredients such as PVP resins which are essential to th e invention at hand. PVP polymers complex with. un~neiilra.l ϊmd polyaeryiic acid polymers to prevent ionization of the polymer backbone. Without ionization of the polymer, uncoiling of the polyacryϋe acid molecule cannot take place. This uncoiling is required for thickening of aqueous solutions. For this reason, the tooth whitening composition of the present invention is preferably generated in distinct phases, with the neutralization of the polyacryiic acid polymer preferably taking place in a phase prior to and separate from the combination with the PVP/hydrogen peroxide complex. By incorporating the polyacryiic acid polymer into the composition after the PVP/byάrogeα peroxide complex Ms been combined with the aqueous hydrogen peroxide,, the level of polyaeryiic acid can be significantly reduced within the end use whitening composition. The preferred composition comprises a polyacrylJc acid polymer from about 0.01% to L 50% by weight of the final composition.

(0036} The preferred composition, may also include a combination of a carrier and an hygroscopic agent that enable the composition to retain its aqueous properties and work synergistically with the thickening agent s in order to remain Theologically active, Carriers generally form the base of the whitening composition, enabling ail of the subsequent ingredients to be contained in a uniform and homogeneous mass, As the term implies, an aqueous whitening composition comprises a water-based carrier which would contain water or water in combination with other carrier ingredients, ϊn addition to wafer, other carrier ingredients may include, but are not limited to_* humectants or hygroscopic agent s such as polyols_, including glycerol_, sorbitol, poly ethylene glycols, propylene glycol, and the like. Preferrably the hygroscopic agent comprises from approximately .1.0% to 10.0% by weight of the total composition weight.

[0037] Additionally, surface active agents such as wetting agents and emulsifiers, including ionic or «on-io»ic surfactants, may be included within the carrier base, In t he whitening composition of th e present invention, the carrier group is selected from purified water with άeiomzed ultra-filtrated water the roost preferred and a poiyhydrie alcohol, glycerin. This combination has proven to be the best combination for extended, elevated temperature stability.

(0038] 'The present tooth whitening composition also preferably contains at least one bleaching agent stabilizer. And, the use of two specific stabilizers enables the gel formula to survive extended periods of time at elevated storage temperature conditions, It has b^en well documented that the use of bleaching agent stabilizers, which mainly comprise chelating agents. can increase the stability of tooth whitening compositions. Bleaching agent stabilizers function primarily by tying up errant metal ions that can catalyze the decomposition process of hydrogen peroxide. Preferably, the bleaching agent stabilizers) comprises approximately from 0.01 % to 1.00% by weight of the total composition weight In addition, in the preferred embodiment, the chelating agent (s) comprises approximately from 0.01 % to 0.50% by weight of the total composition weight. Examples of suitable bleaching agent stabilizers are amiπoearboxyh^'c acids and their salts such as EDTA., EDTA disodium, EDTA, tetrasodium, calcium disodium EDTA and similar EDTΛ compounds, carboxyϋc acids and their salts such as citric acid, gluconic acid, sodium citrate, sodium gluconate and the like as well as tin compounds such as sodium starmate and potassium siaimate.

[0039] The preferred composition .may also include ethylenediatnmetetraaceUc- acid, disodium salt, also known as edetate disodium or disodium EDTA, in combination with i- hydroxyethane-1 _?1 ,-diphosphonic acid, referred more commonly to as etidronic acid. It is the combination of these two ingredients in a precise ratio to the available hydrogen peroxide within the formula that enables th e stability of the composition to be attained. It has been found that a co.mbinat.ion of these two bleaching agent stabilizers in. a ratio of about 30 parts available hydrogen peroxide Io about I part combined stabilizers up to about 40 parts available hydrogen peroxide to about 1 part combined stabilizers will produce an elevated temperature stable whitening geϊ for an excess of 12 weeks at 40 degrees C for a bleach composition of the present invention with an available hydrogen peroxide content of about 28 to 32% of the total bleach composition . The preferred ratio for the composition is about 35; 3 to about 40:1 available hydrogen peroxide to combined stabilizers, with a ratio of about 38:1 the most preferred. However, it has been shown that the ratio of available hydrogen peroxide to bleaching agent stabilizers will function as a sliding scale with a greater ratio existing for bleach compositions exhibiting lower available hydrogen peroxide concentrations and a lower ratio for compositions containing higher levels of available hydrogen peroxide content. This, window will exist for the present invention until ultimately compositions formulated outside the acceptable window will fail under elevated temperature stability testing. For example, it has been shown that a. tooth bleach gel composition of the present invention containing about I 5-20% available hydrogen, peroxide will exhibit stability of an excess of 9 weeks at 47 degrees C with, a ratio of about 45.63: i to about 56.43:1 available hydrogen peroxide to bleaching agent stabilizers. Conversely, a tooth bleach get of the present invention containing aboxjt 32-35% available hydrogen peroxide will exhibit stability in excess of 7 weeks at 40 degrees C with a. ratio of about 26.71 : 1 to about 32.59: 1 available hydrogen peroxide to bleaching agent stabilizers. Thus, it can be assumed that tooth bleaching compositions of the present, invention with hydrogen peroxide contents from about 15% to about 35% can remain stable under elevated storage temperature conditions from 40 degrees C to 47 degrees C by maintaining a ratio of about 25:1 to 60: 1 hydrogen peroxide to bleaching agent stabilizers wt thin the formula.

}^"0040| Formulas that have been generated utilizing ratios beyond these preferred ranges have resulted in predictable failure of the whitening composition at elevated storage temperatures. Sample formulas were prepared on a weight/weight basis utilizing identical ingredients, varying only the percentages of the stabilizers contained within t he preparation. Formulas were all buffered to a final pH of approximately 6.0 to 6.5. Only formulas that contained the two above mentioned stabilizing agents, present in the above mentioned ratios of hydrogen peroxide to combined stabilizers, survived long term stability under elevated storage conditions. {00411 The composition of the present invention, also contains a basic agent which adjusts the pH of the fins! whitening composition. Strong bases generally are used to buffer the acidic nature of hydrogen peroxide solutions. Additionally,, when forming gels with poiyacrylic acids, neutralization of the polymer chain must occur for thickening to take place. Preferrabiy, the neutralizing agent comprises from 0.50% to 5.00% by weight of the total composition weight Suitable basic agent s for tooth whitening compositions are sodήitn hydroxide, ammonium hydroxide,, trieth&nol amine, monoethaaot amine, potassium hydroxide, sodium carbonate, trisodium phosphate and the like. The preferred basic agent for the whitening composition at hand is ammonium hydroxide solution,

EXAMPLES OF THE PREFERRED COMPOSITION.

|O042| The compositions of stable tooth whitening gels capable of maintaining stability at elevated storage temperatures for an extended period of time are as .fallows'.

(0043} The formulas below were all mixed utilizing aoa-metal components in order to minimize the chance of introducing errant metal ions into the composition. ASI mix vessels, spatulas m\d storage containers were constructed of either high density polyethylene or polypropylene. Care was taken to mix all formulas slowly arid methodically in separate phases wi th pure ingredients, minimizing the possibility of entrained air and t he contamination of macro-particles with large surface areas such as dust,

[O004] The following formulas were blended, titrated for available hydrogen peroxide and filled into 3cc clear, HDPE Lauer-iock syringes affixed with a plunger. All plunger locations were marked on the syringe body in order to determine any movem ent of the plunger due to the decomposition of hydrogen peroxide into oxygen gas. Syringes were placed into a stability oven set to 40⁰C with 35% relative h umidity and observer daily for plunger movement or viscosity breakdown. Samples syringes were pulled at 2 weeks, 4 weeks,. 6 weeks, ϊ 0 weeks and 12 weeks and titrated for available hydrogen peroxide. Viscosity observations were determined by extruding the whitening composition onto a glass slide and placing the slide in a vertical position to determine if the gel remained m tact for a 5 minute tim e period without cascading down the glass slide.

EXA1V1PLE.1;.

Phase I:

6.17% Glycerin

1.29% CarbopoJ 934P NF

12.81% Disodium EDTA Solution (3%) in DIUF water

.12.83% Etidronic Acid Solution (3%) in DIUF water

1.38% Ammonium Hydroxide Solution (26 Baume)

Phase 2:

55.03% Hydrogen Peroxide Solution 50%

10.19% Peroxydone XL-IO (FVEVH2O2 Complex)

Phase 3:

Add Phase 1 into Phase 2 with slow agitation Mix mi til homogeneous

0.30% Buffer pH to 6.0 to 6.5 with Arrmioiiiirm Hydroxide Solution (26 Baume) [0045] The above formula titrated to 29.90% available hydrogen peroxide with an initial pH of approximately 6.5. It survived for an excess of 12 weeks at 40*C with no appreciable !oss of hydrogen peroxide content, viscosity or pE. This formula provides a ratio of available hydrogen peroxide to peroxide stabilizers of approximately 38.37:1.

HXAMPLB 2: Phase !:

5.44% Glycerin

1.47% Carbopoϊ 934P W? .13.01% Disodϊum EDTA Solution (3%) in DIUF water

13.17% Etidronic Acid Sol utkm (3%) in DlUP water

1.29% Ammonium Hydroxide Solution (26 Baumό)

Phase 2: 54.90% Hydrogen Peroxide Solution 50%

10.20% Peroxydone XL- 1.0 (PVP/H2O2 Complex)

Phase.3;

Add Phase 1 into Phase 2 with stow agitation Mix until homogeneous

0.52% Buffer pH to 6.0 to 6.5 with Ammonium Hydroxide Solution (26 Baume)

[0046] The above formula titrated to 29.37% available hydrogen peroxide with an initial pH of approximately 6.4. It survived for aa excess of 12 weeks at 40°€ with no appreciable loss of hydrogen peroxide content, viscosity or pH This formula provides a ratio of available hydrogen peroxide to peroxide stabilizers of approximately 38.19: 1. EXAMPLE 3: Phase 1:

5.35% Glycerin

1 ,28% Carbopot 934P NF 12.79% Disodium ED FA Solution (3%) m DIUF water

.12.72% Etidronic Acid. Solution (3%) in DfUF water

2.12% Ammonium Hydroxide Solution (30%)

Phase 2ι 53.65% Hydrogen Peroxϊde Solution 50%

10.00% Psroxydone XL-10 (PVP/H2O2 Complex)

Phase 3:

Add Phase 1 into Phase 2 with slow agitation Mix until homogeneous

2.09% Buffer p.H to 6.0 to 6.5 with Ammonium Hydroxide Solution (30%)

|0047| The above formula titrated io 27.92% available hydrogen peroxide with an initial pH of Approximately 6.5. It survived for an excess of 12 weeks at 4G^σ€ with no appreciable loss of hydrogen peroxide content , viscosity or pM. This formula provides a ratio of available hydrogen peroxide to peroxide stabilizers of approximately 37.35:3.

EXAMPLE 4: Phase 1:

5,11% Glycerin

1.25% Carbopoi 934P NB

12.49% Disodium EDTA Solution Q %) in DIUF water

12.53% Etidfonic Acid Solution (1%) in DIUF water 2.07% Ammonium Hydroxide Solution (30%) Phase 2:

53. ϊ 8% Hydrogen Peroxide Solution 50%

10.01% Feroxydooe XL-IO (PVP/H2O2 Complex)

Phase 3:

Add Phase 1 into Phase 2 with slow agitation

Mix until homogeneous

3.36% Buffer pH to 6.0 to 6.5 with Ammonium Hydroxide Solution (50%)

[0048] The above formula titrated to 28.23% available hydrogen peroxide with an initial pH of approximately 6.5. It survived for 9 days at 40⁰C. The plungers all were displaced from the syringe body with gel expelling from the syringe. The pH of the gel had dropped to approximately 5.0. This formula provides a ratio of available hydrogen peroxide to peroxide stabilizers of approximately 1X2.9S: ! .

EXAMPLE 5: Phase 1:

5.44% Glycerin

1.28% Carbopol. 934P MF

13.28% Disodium EDTA Solution (5%) in DIUF water

13.1.8% Etidronic Acid Solution (5%) m DIUF water 1.19% Ammonium Hydroxide Solution (26 Baume)

Phase 2:

53.59% Hydrogen Peroxide Solution 50%

10.21% Pemxydone XL-IQ (PVP/H2O2 Complex) Phase 3:

Add Phase 1 into Phase 2 with slow agitation Mix until homogeneous

1.83% Buffer pH to 6.0 to 6.5 with Ammonium Hydroxide Solution (26 Bauroe)

(0049} The above formula titrated to 28.43% available hydrogen peroxide with an initial pH of approximately 6.4. Ii survived for 6 weeks 4 days at 40°C. The plungers all were displaced from the syringe body with gel expelling from the syringe. The pH of the gel had dropped to approximately 5,2. This formula provides a ratio of available hydrogen peroxide to peroxide stabilizers of approximately 21.68: L

EXAMPLE S. Phase 1 :

7,08% Glycerin

1.37% Carbopαl 9341? NF

17.12% Disodium EDTA Solution (1%) in DIUF water

17. ϊ 5% Eiidronie Acid Solution (1 %) m DIUF water 0.93% Ammonium Hydroxide Solution (26 Baυmέ)

Phase 2:

44.57% Hydrogen Peroxide Solution 35%

7.27% Peroxydorie XL-10 (FVP/H2O2 Complex)

Phase 3:

Add Phase I into Phase 2 with slow agitation

Mix until homogeneous 4,51 % Buffer pH to 6.0 to 6.5 with Ammonium Hydroxide Solution (26 Baume)

[0050J The a bove formtila titrated to I 7.142% available hy drogen peroxide wifh an initial pH of approximately 6.4. It survived for a» excess of 9 weeks at 47°C with no appreciable loss of hydrogen peroxide content, viscosity or pH. This formula provides a ratio of available hydrogen peroxide to peroxide stabilizers of approximately 49.63; \ .

(005Jj It will be appreciated by those skilled in the art that changes couid be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it. is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

CLAIMS What is eMme4:

1 ! . A high-temperature stable, one-part, aqneous tooth hiesdhϊng composition for contacting a tooth surface comprismg: a bleaching agent comprising a high level of a aqueous hydrogea peroxide, the bleaching agent being derived from multiple components within the composition and comprising at least about 15% by weight of the total, composition weight; and a bhϊizhing agent stabilizer comprising from about 0.01% to about 1.00% by weight of the total composition weight

.1 2, The tooth bleaching composition according to claim 1, wherein the- Meschfctg

2 agent stabilises¹ comprises a ϊ : 1 ratio of ed.3y!enediam«iet«-raacetto ae:id, disodium salt ajjd

3 etidromo acid

1 3. The tooth bleaching composition, according to claim 2. wherein i:h« ratio of

2 hydrogen peroxide to bleaching agent sfehilfeef is sbout 25: 1 to about 60; 1

1 4 The tooth bleaching composition according to claim I, wherein the ratio of

2 hydrogen peroxide to bleaching ageoi stabiføer h about 25: 1 to about 60; I ϊ 5. The tooth bleaching composition according to claim i . foπlϊef comprising a

2 piuKility of thick^ing agents, the thiek&aisg agents comprising at least a crosslinked

3 polyacrylic acid polymer and a polyplasdone hydrogen peroxide complex.

1 6. The tooth bleaching composition according to claim 5, wherein the crosslinked polyacrylic acid thickening agent comprises, less than about 1.50% by weight of the total composition weight

1 7. The tooth bleaching composition according to clai m6 wherein the thickening

2 agents comprise from about 5,0% to about 50.0% by weight of the total composition weight

.! 8. The tooth bleaching composition accordingg to claim 5, wherein the polyplasdone hydrogen peroxide -complex comprises at least about 10.0% by weight of tbe total exrøpositiøn weight.

1 9. The tooth bleaching composition according to claim l_y wherein the bleaching

2 agem stabilizer is $efected from a group consisting of ethylenediaminetetraacetic acid

3 disodium salt; ethylenediaminetetraacetic acid, tetrasodium salt, ethylenediaminetetraacetic acid, calcium di^'sodismst salt; etidronic acid; citri c acid gluconic acid sodium citrate; sodium

5 gluconate; sodium phosphate; disodumi phosphate; Imodium phosphate; tetrapotassium

6 pyrophosphate; sodium tripolyphosphate potassium stannate

1 10. The tooth bleaching composition according to claim 1, furthe comprisin at least

2 one chelating agsnt selected from the group consisting of ethylenediaminetetraacet icid_N

3 disodium ssSt; ethylenediaminetetraac etic tetrasodium salt; ethyl enediaminetetraaceticc

4 acid, calcium di&odimn salt; citric acid; glucom^'c- acid; sodhsrs* ctete; sodium gluconate;

3 sodium phosphate; disodiu mhosphate; tri&od^'mm phosphat e-^rspolsssjutn pyrophosphate;

6 a#d sodium tdpofyphospfeate.

1 1 1, Th^ iooth bleachmg composition accordiftg to claim 10, wherein the at least one-

2 chelating agent comprises from about 0.0i% to about 0.50% by weight of the tota^

3 composition v^ight

.1 12, The tooth bleaching composition according to claim ϊ , ftsrtte comprising at least

2 one chelating agent the chelating agent fbeing disodiumo. E.DTA.

1 13. The tooth bleaching composition, according to claim 1 _> further comprising at Ieast

2 one hygroscopic agent selected from the polyol group consisting of glycerin, polyethylene

3 glycol propylene glycol and sorbitol. ϊ 14, The tooth bleaching composition aeco*<Ji»g to claim 13, wherein the- at least one

2 hydroscopic agent comprises from about 1. 0% to about 10.0% by weight of the total

3 composition weight

1 15. The tooth bleaching composition according to claim 14, wherein the at least one

Z .hygroscopic agent is glycerin..

1 Kh The tooth bleaching composition according to claim 1 , furtherc omprisingg at least

2 one neutralizing agent selected from a group consisting of toethanokmine, tromethamine ,

3 sodhjui hydroxide, potassium hydroxide, and ammomaia hydroxide.

17. The tooth bleaching co mposition according to claim 16, whereinthe at least one neutralizing agent adjusts the pH of the final tooth, whitening composition between about 6.0 to about 7.0. 18, The tooth bleaching composition according to claim 16, wherein the at least one neutralizing agent comprises from about 0,50% to about 5,00% by weight of the total composition weight. 19. The tooth bleaching composition according to clai m 16, wherein the at least one neutralizing agent is ammonium hydroxide. 20. The tooth bleaching composition. according to claim I, wherein the bleaching agent is derived from multiple components within the composition including an aqueous hydrogen peroxide, a polypiasdone hydrogen peroxide complex; a polyacryhc acid polymer; water, glycerin, ethylenediaminetetracenic acid disodium salt; etidronic acid and ammonium, hydroxide. 21 The tooth bleaching composition according to claim 1, further comprising at least one chelating agent the chelating agent being etidronic acid 22. A high-temperature stable, one-part, aqueous tooth, bleaching composition for contacting a tooth surface comprising; s bleaching agent comprising a high level of a aqueous hydrogen peroxide, the bleaching agent being derived from multiple components within the composition and comprising at least about 15% by weight of the total composition weight and a bleaching agent stabilizer comprising, the bleaching agent stabilizer comprises a 1 ; 1 ratio of eethylenediaminetetraacetic acid, disodium salt and etidronic acid, and the ratio of hydrogen peroxide to bleaching agent stabilizer is about 25: 1 to about 60; 1 ; and a plurality of thickening agents, the thickening agents comprising at .test a crosslinked polyacrylic acid polymer and a polyplasdone hydrogen peroxide complex. 23. The tooth bleaching composition, according to claim 22, wherein the thickening agents comprise from, about 3.0% to about 50.0% by weight of the total composition weight and wherein the polyplasdone hydrogen peroxide complex comprises at least about 10.0% by weight of the total com position weight.

3 24. The tooth bleaching composition according to claim 22, further comprising at

2 least one hygrocscopic agent selected from the polypol group consisting of glycerin,

3 polyethylene glycol_, propylene glycol and sorbitol, the at least one- hydroscopic agent

4 comprises from about 1 ,0% to about 10,0% by weight of the total composition weight

1 25. The tooth bleaching composition. accordin to claim 23, further comprisin gg

2 least one hygroscopic agent selected from the polyol group consisting of glycerin,.

3 polyethylene glycol, propylene glycol and sorbitol the at leasr one hydroscopic agent A comprises from about 1.0% to about 10.0% by weight of the total composition weight.

.1 26. The tooth bleaching composition according to claim 22_, further comprising at

2 least one neutralizing agent selected from a group consisting of triethynolamine,,

3 tromethambe, sodium hydroxide, potassium hydroxide, and ammonium hydroxide, the at

4 least one neutralising agent adjusts the pH of the fmal tooth whitening composition between

5 about 6.0 to about 7.0,

1 27, The tooth bleaching composition according to claim 25 farther comprising at least

2 one neutralizing agent selected from a group consistingo ft riethynolamine tromethamine,

3 sodiumo hydroxide, potassium hy<droxide, and ammoniumm hydroxide the at least ose

4 netnraiizirsg agent adjwsts the pH of the tlmϊl tooth whitening composition between about.6.0 3 to about.7.0,

3 28. The tooth bleaching composition according to claim 27, wherein the at least one

2 neutralising agent is ammonium hydroxide nnύ the at least oκe hydroscopic agestt is glyoeri«.

.1 29, The tooth bleaching composition aceoκli»g to claim 2$, wherein the thickening

2 age«& comprise from about 5.(Bi to shout .50.0% by weight of the total composkio« weight,

3 the crossiisked polyaccylic acid thickeoing agent comprises less than abom 1.50% by weight

4 of the total composition weight, and the polyplasdαne hydrogen peroxide complex comprises

5 at feast, about 10.0% by weight of thfe total composition weight; the at least one hydroscopic

6 agent comprises from about 1 0% to about \ 0.0% by weight of the total composition weight; ? &nά the at least one n&utralizmg agast comprises from about (150% to about 5.00% by

8 weight of the total composition weight